Variable density image processing apparatus

ABSTRACT

For forming multiple images on a single sheet of film (F) for medical use, specific data to the film (F) such as a patient name are extracted from one of the images, and the extracted data are enlarged, and the enlarged data are output to an optical processing system, of which exposing position is controlled, and then the data is exposed onto the film (F) in a designated location, for example, at the bottom of the film (F) thereby.

This is a division of application Ser. No. 08/525,752 filed Oct. 4, 1995now U.S. Pat. No. 5,724,153.

TECHNICAL FIELD

This invention concerns a variable density image (grey scale image)processing method and an image processing apparatus which utilizes thatmethod. More specifically, it concerns a variable density image (greyscale image) processing method, and variable density image (grey scaleimage) processing apparatus utilizing it, which can render identifiablea single-sheet photosensitive medium on which multiple images have beenmade, by simply and rapidly inscribing identifying information in adesignated location on the medium.

This invention also concerns a more compact, lightweight variabledensity image (grey scale image) photographic apparatus capable ofutilizing this variable density image (grey scale image) photographicapparatus.

BACKGROUND ART

In the medical field, an image created by imaging technology such asX-ray computed tomography (CT), scanning-type nuclear magnetic resonanceimaging (MRI), and digital subtraction angiography (DSA), after beingconverted to a digital image and magnified by a designated multiplier bymeans of a variable density image (grey scale image) processingapparatus, is broken down into its constituent graphic elements. Thedigital image data, containing that image's continuous series ofgradients, is converted into a chronological series of analogue signals.An apparatus called a laser imager (hereinafter termed a "variabledensity image photographic apparatus") then uses a semi-conductor laserapparatus (cf. FIG. 20), employing a direct modulation formula, toirradiate silver-sodium film with these analogue signals, thus makingthem into photographs.

Each original image includes within it certain data specific to itself,as for example its identification number, patient name, or the date theimage was created (cf. FIG. 21). However, the laser beams of the opticalsystems used in these variable density image (grey scale image)photographic apparatus range between about 80 μm and 100 μm in diameter;in consequence, a written (i.e. alphabetic or numeric) character of the16-dot size commonly used, for instance, comes out to a size ofapproximately 1.2 mm when inscribed by such a beam. As a result, areader cannot decipher the data on the film simply by looking at thefilm.

Thus, at present, data used for identification of individual films(hereinafter termed "identifying data") is input by means of thevariable density image (grey scale image) processing apparatus inputapparatus, and is inscribed onto the bottom of the film in a fixed sizeby means of the optical system; or, alternatively, an identificationlabel is affixed to the bottom of the film following development.Although the data is then readable, the process interferes with therapid handling of such medical films.

In their typical configurations, the basic constituents of the variabledensity image (grey scale image) photographic apparatus currently in useare as follows:

(1) a film feeding cassette for storage of film prior to exposure;

(2) a pick-up mechanism to remove the film from the film feedingcassette;

(3) a feeding means for feeding the film removed by this pick-upmechanism to the target location of the laser beam;

(4) an exposure means to expose the film by scanning it whileirradiating it with a laser beam;

(5) a film securing means to secure the film;

(6) a secondary scanning means to scan the film in a directionperpendicular to the laser beam's direction of scan;

(7) a retrieval means for retrieving the exposed film;

(8) a film retrieval cassette for storage of film following retrieval;

(9) an image processing means for laser-scan modulation, assembling ofimage data, and image enlargement and reduction;

(10) a control means for control of laser output and other means;

(11) a power supply means for the controls, for laser output, and foroperating the apparatus.

FIGS. 22-26 show examples of variable density image (grey scale image)photographic apparatus configured from the constituents described above.

FIG. 22 depicts a variable density image (grey scale image) photographicapparatus i, consisting of a film feeding cassette a, a film retrievalmeans b, an exposure means c, an image processing means d, and acontrol/power supply means e, configured from top to bottom in thatorder, and a film securing drum f, located next to the image processingmeans d. The various means in the variable density image (grey scaleimage) photographic apparatus i in FIG. 22 are thus stacked one on topof another, resulting in a height of approximately 1,200 mm and a weightof some 290 kg. Symbol p in FIG. 22 represents a pick-up mechanism, andg represents a film conveyor means which feeds and also retrieves thefilm.

FIG. 23 depicts a variable density image (grey scale image) photographicapparatus i, consisting of a film feeding cassette a, an exposure meansc, a film shape adjustment space s, a film securing and conveying meansh which both secures and conveys the film, and an image processing,control, and power supply means j, configured from top to bottom in thatorder, and with a separate automatic development apparatus placed nextto the variable density image (grey scale image) photographic apparatus.The film which has been developed by this automatic developer isretrieved in the tray t, located on top of variable density image (greyscale image) photographic apparatus i. Thus FIG. 23's variable densityimage (grey scale image) photographic apparatus, like that shown in FIG.22, has its components stacked one on top of another; moreover, there isa film shape adjustment space s located between exposure means andfilm-securer and conveyor means h, resulting in a height ofapproximately 900 mm and a weight of approximately 250 kg. In addition,the height of the automatic development apparatus is approximately 1250mm; the total weight comes to roughly 500 kg. Symbol p in FIG. 23represents a pick-up mechanism, and g represents a film conveyor means.

FIG. 24 depicts a variable density image (grey scale image) photographicapparatus i, consisting of a film feeding cassette a, a film-shapeadjustment space s, and a film securing half-cylinder k, configured fromtop to bottom in that order, with an exposure means c located in thecenter of the half-cylinder k, and with an image processing, control,and power supply means m located adjacent to the film shape adjustmentspace s and film securing means k. An automatic development apparatus ismounted on top of variable density image (grey scale image) photographicapparatus i, so that the total height of variable density image (greyscale image) photographic apparatus i, including that of the automaticdeveloper, comes to approximately 1,500 mm, and their combined weightcomes to approximately 370 kg. Symbol p in FIG. 24 represents a pick-upmechanism, and g represents a film conveyor means.

FIG. 25 depicts a variable density image (grey scale image) photographicapparatus i, consisting of an exposure means c, a film securing drum f,a film retrieval cassette b, a film feeding cassette a, and an imageprocessing, control, and power supply means m, configured from top tobottom in that order. For this reason, the height of variable densityimage (grey scale image) photographic apparatus i is approximately 1,030mm, and its weight is approximately 180 kg. Symbol p in FIG. 25represents a pick-up mechanism, and g represents a film conveyor means.

FIG. 26 represents a variable density image (grey scale image)photographic apparatus i, consisting of a film feeding cassette a, afilm securing quarter-cylinder n with a revolving type exposure means c,and an image processing and power supply means o, configured from top tobottom in that order, with a control means q installed adjacent to thefilm securing quarter-cylinder n. As a result, this variable densityimage (grey scale image) photographic apparatus i measures roughly 1,280mm in height, and its weight is approximately 170 kg. Symbol p in FIG.26 represents a pick-up mechanism, and g represents a film conveyormeans.

Thus, the conventional variable density image (grey scale image)photographic apparatuses i exceed 1 meter in height and weigh around 200kg. Their large size gives rise to certain problems: they require alarge space in which to be installed; efficient utilization of floorspace and room space is reduced in the facilities in which they areinstalled; and shipping and moving of these apparatuses is a complex andexpensive undertaking.

For these reasons, the advent of an easy-to-handle variable densityimage (grey scale image) photographic apparatus measuring less than 1meter in height and weighing under 100 kg will be warmly welcomed bymedical professionals who deal with medical equipment of this type.

In developing this invention, we have sought to learn from such problemswith the prior art. The object of this invention is to offer a variabledensity image (grey scale image) processing method, and a variabledensity image processing apparatus utilizing it, which can renderidentifiable a single-sheet photosensitive medium on which multipleimages have been made, by simply and rapidly inscribing identifyinginformation in a designated location on the medium.

An additional object is to provide a variable density image (grey scaleimage) photographic apparatus which can make photographs out of imagesfrom variable density image processing apparatus and which is smallerand more lightweight, thus enhancing the efficient utilization of floorand room space in facilities in which it is installed, and improvingease of shipping and moving.

DISCLOSURE OF THE INVENTION

As a result of extensive research into these problems, the inventorshave found that in as much as each image, as discussed above, containsdata specifying its own identifying data, such as identification number,patient name, creation date, etc., the problems discussed above could besolved by a more flexible disposition of such data. That idea led to thedevelopment of this invention.

A variable density image (grey scale image) processing method of thisinvention is thus a variable density image (grey scale image) processingmethod intended as an image processing method for a single-sheetphotosensitive medium on which multiple images are made. Its distinctivefeature is that it includes a procedure for formulating digital imagesout of images input from an imaging means, a procedure for selecting aspecific image from among these multiple images, a procedure forextracting from the graphic data of that selected image a certainspecific zone of graphic data, a procedure for converting the specificzone of data thus extracted into digital data enlarged by a designatedmultiplier, and a procedure for outputting this converted image of thespecific zone of graphic data to an optical processing system.

It is preferable that the variable density image (grey scale image)processing method of this invention is supplemented by a procedure forremoving any non-character data (i.e. data other than letters, numbers,etc.) which may be included within the specified zone of graphic data.

Moreover, a variable density image (grey scale image) processingapparatus of this invention is a variable density image (grey scaleimage) processing apparatus which can be used to form multiple images ona single-sheet photosensitive medium. A distinctive feature is that itis equipped with an original image memory means, a Number 1 imageprocessing means, a Number 2 image processing means, an image outputmeans and input means, and an arithmetic processing means, where theidentifying data processing means

identify data specific to the multiple images are extracted therefrom;

enlarge the extracted identifying data by a designated multiplier; and

the enlarged identifying data at a designated location on thephotosensitive medium.

It is preferable that variable density image (grey scale image)processing apparatus of this invention is supplemented by a removalmeans for removing any non-character data which may be included in theidentifying data.

The distinctive feature of variable density image (grey scale image)photographic apparatus of this invention is that it is equipped with afilm feeding means, a film retrieval means, an image processing means,an exposure means, a control means, a power supply means, and a filmconveyor means, and that the film feeding means and the film retrievalmeans are set at a fixed interval from one another, with the exposuremeans placed between them.

It is preferable for variable density image (grey scale image)photographic apparatus of this invention that the film is exposed by theexposure mechanism while being conveyed by the film conveyor means.

It is also preferable for variable density image (grey scale image)photographic apparatus of this invention that the conveyor means isequipped with a conveying mechanism having at least one pair of rollers,stretched over a soft and pliable belt, somewhat wider than the conveyedfilm, on the side of the film where its edges curl.

In addition, for the variable density image (grey scale image)photographic apparatus of this invention, this belt is preferably set inthe target location of the exposure means.

Because the variable density image (grey scale image) processing methodof this invention includes all of the procedures described above, it isable to extract from among the images formed on a photosensitive mediumthe data which typifies that medium, e.g. identification number, patientname, image creation date, etc.; to enlarge that data to a size whichcan be read by the unaided eye; and to instruct the optical processingsystem which exposes the medium to inscribe that data onto the medium ata designated location, such as the bottom part of the medium.

Since data other than written characters may be included in theinformation thus extracted, the variable density image (grey scaleimage) processing method of this invention can, in its preferableaspect, be instructed to remove such non-character data, so that onlycharacter information is inscribed onto the designated location on thephotosensitive medium.

The variable density image (grey scale image) processing apparatus ofthis invention is configured as described above, and is therefore ableto extract from among the images formed on the photosensitive medium thedata which typifies that medium, such as identification number, patientname, image creation date, etc.; to enlarge that data to a size readableby the unaided eye; and to then output that data to an opticalprocessing system as instruction data to be inscribed onto thephotosensitive medium at a designated location, for instance at thebottom of the medium.

The data thus extracted may include non-character information; however,in a preferable aspect of variable density image (grey scale image)processing apparatus of this invention is able to remove suchinformation, outputting only character information to the opticalprocessing system as instruction data to be inscribed onto a designatedlocation on the photosensitive medium.

The variable density image (grey scale image) photographic apparatus ofthis invention is configured as described above, resulting in reductionin both size and weight for the apparatus as a whole.

It is preferable in this apparatus that the exposure of film takes placein the space between the film feeding cassette and the film retrievalcassette.

In a preferable aspect of variable density image (grey scale image)photographic apparatus of this invention, exposure of the film takesplace while the film is being conveyed; hence there is no need to stopthe film to allow it to be exposed, and processing time is shortened.

In another preferable aspect of variable density image (grey scaleimage) photographic apparatus of this invention, a belt is used toprevent curling of the edges of film, allowing the images to beinscribed onto stabilized film.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 is a block diagram of an image processing apparatus used in imageprocessing method of this invention.

FIG. 2 is a block diagram of an original image memory processing means.

FIG. 3 is a block diagram of a Number 1 image processing means.

FIG. 4 is a block diagram of a Number 2 image processing means.

FIG. 5 is a block diagram of an image output means.

FIG. 6 is a block diagram of identifying data processing means.

FIG. 7 is a schematic illustration of one embodiment of image processingapparatus shown in FIG. 1 in a software configuration.

FIG. 8 is an explanatory illustration of film with data inscribed ontoit by variable density image (grey scale image) processing method ofthis invention.

FIG. 9 is a part of a flowchart showing one example of the imageprocessing procedure used in variable density image (grey scale image)processing method of this invention.

FIG. 10 is a part of a flowchart showing one example of the imageprocessing procedure used in variable density image (grey scale image)processing method of this invention; it is a continuation of theflowchart shown in FIG. 9.

FIG. 11 is a part of a flowchart showing one example of the imageprocessing means used in variable density image (grey scale image)processing method of this invention; it is a continuation of theflowchart shown in FIG. 10.

FIG. 12 is an image illustration of image processing in image processingmethod of this invention, showing the image prior to alteration.

FIG. 13 is an image illustration of image processing in image processingmethod of this invention, showing the image after setting horizontalgrid point density.

FIG. 14 is an image illustration of image processing in image processingmethod of this invention, showing the final image after setting verticalgrid point density as well.

FIG. 15 is an explanatory illustration of the density arithmetic methodfor newly generated grid points.

FIG. 16 is a weighted function graph.

FIG. 17 is a cross-sectional view of one embodiment of variable densityimage photographic apparatus of this invention.

FIG. 18 is a cross-sectional illustration of a main part of the sameembodiment.

FIG. 19 is an explanatory illustration of a pick-up mechanism of thesame embodiment.

FIG. 20 is a schematic illustration of one example of an exposureapparatus.

FIG. 21 is an explanatory illustration of images inscribed on film by aconventional image processing methods.

FIG. 22 is a schematic cross-sectional view of Example No. 1 of aconventional variable density image (grey scale image) photographicapparatus.

FIG. 23 is a schematic cross-sectional view of Example No. 2 of aconventional variable density image (grey scale image) photographicapparatus.

FIG. 24 is a schematic cross-sectional view of Example No. 3 of aconventional variable density image (grey scale image) photographicapparatus.

FIG. 25 is a schematic cross-sectional view of Example No. 4 of aconventional variable density image (grey scale image) photographicapparatus.

FIG. 26 is a schematic cross-sectional view of Example No. 5 of aconventional variable density image (grey scale image) photographicapparatus.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, referring to the drawings attached hereto, this invention isdisclosed below on the basis of an embodiment, however, the scope ofthis invention is not only limited to the embodiment.

FIG. 1 shows a block diagram of the variable density image (grey scaleimage) processing apparatus to be used for the variable density image(grey scale image) processing method of this invention.

The variable density image processing apparatus comprises an originalimage memory means 1, a Number 1 image processing means 2, a Number 2image processing means 3, an image output means 4, an identifying dataprocessing means 5, an input means 6, and an arithmetic processing means7 as its main constituents.

The original image memory means 1 has a function to temporarily storethe image to be input from an X-ray CT unit or an MRI unit. Accordingly,the original image memory means 1 comprises an A/D converter 11 and aninput-side line memory 12 as its main constituents (cf. FIG. 2). Anoriginal image stored in the original image memory means 1 is input intothe Number 1 image processing means 2 through the signal line, and theoriginal image for extraction of the identifying data is input into theidentifying data processing means 5 through the signal line.

The detailed explanation of the configuration of the A/D converter 11and the input-side line memory 12 is omitted, however, it is suitable touse the devices which are conventionally used for this sort of imageprocessing apparatus.

The Number 1 image processing means 2 has a function to set the densityof the newly generated grid point strings (or, lines) for the imagemodified by a real multiplier, using the density of the strings (or,lines) of the original image's graphic elements which are input from theoriginal image memory means 1. For this, the Number 1 image processingmeans 2 comprises a Number 1 memory 21 which stores the data of originalimage elements, a Number 1 coefficient memory 22 which stores weightedtable or function, and a Number 1 arithmetic device 23 which computesdensity of grid point strings newly generated by the data of originalimage elements and coefficient which is obtained from the weighted tableor function, as its main constituents (cf. FIG. 3). The graphic datagenerated by the Number 1 image processing means 2 is input into theNumber 2 image processing means 3 through the signal lines.

The Number 2 image processing means 3 has a function to set the densityof the grid point lines (or, strings) newly generated by the graphicdata of the grid point strings (or, lines) with the density set by theNumber 1 image processing means 2. For this, the Number 2 imageprocessing means 3 comprises a Number 2 memory 31 which stores thegraphic data of the grid point strings (or, lines) with the set density,a Number 2 coefficient memory 32 which stores weighted table orfunction, a Number 2 arithmetic device 33 which computes density of thegrid point lines (or, strings) without density to be set by thecoefficient obtained from the graphic data of the grid point strings(or, lines) with a set density and weighted table or function, and themodified image memory 34 which stores the modified image with a setdensity, as its main constituents (cf. FIG. 4). The data generated bythe Number 2 image processing means 3 is input into the image outputmeans 4 through the signal lines.

Multiplication by a real multiplier herein means to modify by anarbitrary real multiplier such as by 0.1 . . . 1.5 . . . 2.0 . . . 3.6 .. . 4.0 . . . 4.8 . . . Accordingly, it implies not only enlargement butalso reduction.

The image output means 4 has a function to form a latent image on photofilm by adjusting the modified image which is input from the Number 2image processing means 3 at a designated density and by consecutivelyoutputting each line in a form of analogue signal to the opticalprocessing system (optical processing apparatus). In other words, it hasa function to instruct to inscribe an image on film. For this, the imageoutput means 4 comprises a density adjustor 41 and a D/A converter 42 asits main constituents. When the latent image is formed (inscribed) onphoto film, it includes all graphic data which is stored in the modifiedimage memory 34 of the Number 2 image processing means 3.

The density adjustor (LUT--Look up table) 41 has a function to multiplythe gamma characteristic of photo film and the graphic data which ismodified by a designated multiplier and given a set density in order tomake it easy to be seen, i.e., the graphic data stored in the modifiedimage memory 34 of the Number 2 image processing means 3, by acoefficient in the range between 0 to 1.0 (density adjustment value)computed by a designated density adjustment function. For this, thedensity adjustor 41 has the density adjusting function memory 43 whichrewrites a density adjustment function whenever necessary, anoutput-side line memory 44 which stores the computed graphic data storedin the modified image memory 34 of the Number 2 image processing means 3in a portion of one line, and the multiplying device 45 which multipliesthe graphic data by a density adjustment value (cf. FIG. 5).

The detailed explanation of the configuration of the D/A converter 42,the output-side line memory 44 and the multiplying device 45 is omittedhere, however, it is suitable to use the devices which areconventionally used for this sort of image processing apparatus.

The identifying data processing means 5 has a function to extractidentifying data from the image which is input from the original imagememory means 1, to enlarge the extracted identifying data by adesignated multiplier, and to instruct the image output means 4 toinscribe such enlarged identifying data on a designated location ofphotosensitive medium. For this, the identifying data processing means 5comprises an identifying data memory 51 for storage of the extractedidentifying data, an arithmetic device 52 which enlarges identifyingdata by a designated multiplier, and an enlarged identifying imagememory 53 for storage of the image relating to the enlarged identifyingdata, i.e., the data relating to the enlarged identifying image, as itsmain constituents (cf. FIG. 6).

Following is the explanation of extraction of the identifying data byreference to FIG. 8.

In this case, since multiple images to be inscribed on a single-sheet ofphoto film are of the same person, identifying data can be extractedfrom any one of the images. However, for the sake of convenience in dataprocessing, it is usually extracted from the first image to be firstinscribed on (in the case of FIG. 8, from the image top left-handcorner). Also positioning of the identifying data of the image isunconditionally determined when a format of the image is determined.Format is specific to the type of machine and the hospital to which themachine belongs. Accordingly, identifying data can be extracted bypreliminary instructing to extract data in a certain scope (data from acertain lot number to another certain lot number) of the original imagememory means 1 which stores data relating to the first image, forexample.

The input means 6 has the function to designate an image from whichidentifying data is extracted, a processing method, and a multiplier.The input device 6 with this function can be constituted of, forinstance, a CRT display and a keyboard.

The arithmetic processing means 7 has a function to control input andoutput of the above mentioned means 1, 2, 3, 4, 5, and 6, to modify theoriginal image by a certain multiplier (a real multiplier) through theimage processing method instructed by the input means 6, and to computea clearance between the newly generated grid points and the originalimage elements and a clearance between the grid points with unassigneddensity and those with assigned density. Therefore, the arithmeticprocessing means 7 comprises of a central processing unit (CPU) 71, aRAM, a ROM, and a CLOCK as its main constituents.

For the arithmetic processing device 71, a device which can promptlyprocess a large volume of information should be used. To be morespecific, it can be a parallel processing type computer (a computerwhich can be connected in a parallel line), a vector processing typecomputer, a co-processor which processes a specifically designated job,a DSP (digital signal processor) which directly processes digital valuesinto signals, or a data-flow type computer.

The RAM 72 temporarily stores information necessary to the arithmeticprocessing. It is suitable to use a RAM which is conventionally used forimage processing apparatus.

The ROM 73 stores the program to compute a clearance between the newlygenerated grid points without an assigned density and the original imageelements, or a clearance between the grid points with a set density andthe original image elements, the program to extract identifying datafrom the graphic data of the original image memory means 1, the programto remove data other than characters if they are included in theidentifying data, and the program necessary for controlling operation ofthe above mentioned means 1, 2, 3, 4, 5, and 6. For the ROM 73, it issuitable to use the one which is conventionally used for imageprocessing apparatus.

Removal of data other than written characters can be done by alteringintermediate values except for 1 to 0, since characters are binary.

The CLOCK 74 synchronizes flow of every information, and any deviceconventionally used for this sort of arithmetic processing device suitsthe CLOCK 74.

Program counter and other necessary elements for arithmetic processingare equipped in this image processing apparatus, although it is notillustrated in the drawing.

FIG. 7 depicts a schematic illustration of one embodiment in a softwareconfiguration of the variable density image (grey scale image)processing apparatus as described above.

Following are the steps of image processing with this embodiment of thevariable density image (grey scale image) processing apparatus in theconfiguration as mentioned above.

Step 1: Input an X-ray CT image or an MRI image of analog image into theoriginal image memory means 1.

Step 2: The original image memory means 1 converts the input analogimage to a digital image through the A/D converter 11.

Step 3: Store the data of the image elements of the digital image in theinput-side line memory 12 of the original image memory means 1.

Step 4: Store the data of the original image elements stored in theoriginal image memory means 1 in the Number 1 memory 21 of the Number 1image processing means 2 in a designated arrangement.

Step 5: An image processing method and a multiplier to be used areinstructed from the input means 6.

Step 6: Modify the clearance among the original image elements by adesignated multiplier, and at the same time, generate new grid points inthe modified clearances of the original image elements at a fixedclearance.

Step 7: Compute density for the newly generated grid points through thedesignated processing method. Steps of this process are explained later.

Step 8: Store the modified image of the newly generated grid points withthe set density stored in the modified image memory 34 of the Number 2image processing means 3.

Step 9: Consecutively call the modified graphic data from the modifiedimage memory 34 of the Number 2 image processing means 3, and store itin the output-side line memory 44 of the image output means 4.

Step 10: Consecutively output the data of the output-side line memory44, adjust its density by the density adjustor 41, output it to the D/Aconvertor 42 and convert into an analog image.

Step 11: Output the analog image to an optical processing apparatus (alaser scanning apparatus).

Step 12: From the input means 6, instruct the original image memorymeans 1 as to from which image identifying data is to be extracted, andat the same time instruct the identifying data processing means 5 as towhich processing method and multiplier are to be used. However, asmentioned above, identifying data is usually extracted from the firstimage.

Step 13: Input the designated image into the identifying data processingmeans 5 from the original image memory means 1.

Step 14: The identifying data processing means 5 extracts identifyingdata from the input image, and stores it into the identifying datamemory 51. In case that this extracted data includes data other thanwritten characters, the identifying data processing means 5 removesthose non-character data.

Step 15: Enlarge the clearance among the image elements of theidentifying data by a designated multiplier, and generate new gridpoints in the enlarged clearances at a designated clearance.

Step 16: Compute density of the newly generated grid points through thedesignated processing method. This processing method is the same as thatof Step 7.

Step 17: Store the enlarged image consisting of the newly generated gridpoints with the set density in the enlarged image memory 53.

Step 18: Consecutively call the enlarged identifying graphic data fromthe enlarged identifying image memory 53, and store it in theoutput-side line memory 44 of the image output means 4.

Step 19: Consecutively output the data of the output-side line memory44, adjust its density with the density adjustor 41,output it to the D/Aconverter 42, and convert it into an analog image.

Step 20: Output the analog image to the optical processing apparatus(the laser scanning apparatus).

After Step 20, the image relating to the identifying data which isoutput to the optical processing apparatus is inscribed on, forinstance, an empty space at the bottom of film (cf. FIG. 8). Steps 9, 10and 11 are repeated until the graphic data stored in the modified imagememory 34 is all output.

Following is an example of the image processing procedure used for thisembodiment. It is explained according to the flowcharts of FIGS. 9, 10and 11.

Step 31: Read a designated multiplier.

Step 32: Read a designated image processing method.

Step 33: Set the J at 1. Here, the J represents the string number of theoriginal image elements.

Step 34: Set the i at 1. Here, the i represents the line number of thenewly generated grid points.

Step 35: Compute the clearance between the grid point numbered i and thefour grid points in the nearest neighborhood of the grid point numberedi on the string numbered J.

Step 36: Using a weighted table or a function, compute the coefficientof the above four points using the above computed clearance through thedesignated processing method. For this weighted table or function, thenearest neighborhood method, the linear interpolation method, or thespline interpolation method is used, for example.

Step 37: With the above coefficient and the density of the four originalimage elements, compute the density of the grid point numbered i, andstore it temporarily at the lot number h (i, J).

Step 38: Add 1 to the i.

Step 39: Judge if the i exceeds 4444. If the i does not exceed 4444,return to the Step 35. If the i exceeds 4444, proceed to the next step.Here, 4444 indicates the last line number of the newly generated gridpoints. In this embodiment, the last line is numbered at 4444, however,it can be appropriately set at any other number.

Step 40: Add 1 to the J.

Step 41: Judge if the J exceeds 512. If the J does not exceed 512,return to the Step 34. If the J exceeds 512, proceed to the next step.Here, 512 indicates the last string number of the original image elementstrings. In this embodiment, the last string is numbered at 512,however, it can be set at any number according to the number of theoriginal image element strings.

Step 42: Set the i at 1.

Step 43: Set the j at 1. Here, the j indicates the string number of thenewly generated grid points.

Step 44: Compute the clearance between the grid point numbered j of thenewly generated grid points and four nearest points to the above gridpoint numbered j on the line numbered i which density is set through theabove mentioned process.

Step 45: Using a weighted table or a function, compute the coefficientof the above four points from the above computed clearance through thedesignated processing method. For this weighted table or function, thenearest neighborhood method, the linear interpolation method, or thespline interpolation method is used, for instance. The method used forthis step should be the same method as used for Step 36.

Step 46: With the above coefficient and the density of the above fourgrid points, compute the density of the grid point numbered j, andsubstitute the outputting image element Q (i, j) for the density value.

Step 47: Add 1 to the j.

Step 48: Judge if the j exceeds 5398. If the j does not exceeds 5398,return to the Step 44. If the j exceeds 5398, proceed to the next step.Here, 5398 indicates the last string number of the newly generated gridpoints. In this embodiment, the last string is numbered at 5398,however, it can be set at any other number.

Step 49: Add 1 to the i.

Step 50: Judge if the i exceeds 4444. If the i does not exceed 4444,return to the Step 43. If the i exceeds 4444, finish computing.

The above processed image is illustrated in FIGS. 12, 13 and 14. FIG. 12shows the graphic image before modification. FIG. 13 shows the graphicimage with the density set only horizontally. FIG. 14 shows the finalgraphic image with the density set both in horizontally and vertically.In FIGS. 12, 13 and 14, the blackened circle  indicates a grid point(or image element) with a set density, and the blank circle ◯ indicatesa grid point with an unassigned density.

Following is the density computing method for the newly generated gridpoints in reference to FIG. 15. It is computed according to the nearestneighborhood method, as an example.

In FIG. 15, the lines 5, 6, 7 and 8 of the first string of the originalimage elements are shown, and the point on the 20th line of the firststring is shown as the grid point which needs density setting.

This grid point which needs density setting is away from the imageelements (5, 1), (6, 1), (7, 1) and (8, 1) of the first string by aclearance of -1.3, -0.3, +0.7, and +1.7 relatively.

The coefficients for these clearances are 0, 1, 0 and 0 as shown in thegraph (A) of FIG. 16. The graphs (B) and (C) show the coefficientscomputed through the linear interpolation method and the splineinterpolation method relatively.

Density of the newly generated grid points is calculated using theformula shown below.

    h(i,j)=t.sub.0 x.sub.0 +t.sub.1 x.sub.1 +t.sub.2 x.sub.2 +t.sub.3 x.sub.3

t: Coefficient corresponding to clearance

x: Density of original image elements

subscript 0, 1, 2, 3: Numbers of the original image elements for thenewly generated grid points

Now, substitution of the above computed coefficients and the density ofthe original image elements for the above formula becomes as shownbelow:

    h(20,1)=0·x.sub.0 +1·x.sub.1 +0x.sub.2 +0·x.sub.3

Accordingly, in the above formula the only second term of the rightmember remains, and the density of the grid points is set at the densityof the original image element in the nearest neighborhood. In otherwords, the density is set using the nearest neighborhood method.

Here, the density setting using the nearest neighborhood method is onlyexplained. However, by changing a weighted table or function to beselected, the density for the newly generated grid points can be setthrough the linear interpolation method or the spline interpolationmethod in the same manner.

Following is an explanation of one embodiment of the variable densityimage photographic apparatus which mounts the above mentioned variabledensity image (grey scale image) processing apparatus, referring to theattached drawings.

FIG. 17 shows the cross section of one embodiment, FIG. 18 shows aconstruction of its main part, and FIG. 19 illustrates its pick-upmechanism. In the drawings, 100 represents the main body, 110 representsthe mounting part of the film feeding cassette, 120 represents themounting part of the film retrieval cassette, 130 represents the powersupply means, 140 represents the exposure means, 150 represents theimage processing control means, 160 represents the pick-up mechanism,170 represents the film conveyor means, 180 represents the vibrationisolating means, A represents the variable density image (grey scaleimage) photographic apparatus, F represents the film, FC represents thefilm feeding cassette, and RC represents the film retrieval cassette.

The variable density image (grey scale image) photographic apparatus Ain FIG. 17 is equipped with the mounting part 110 of the film feedingcassette FC which is mounted on the upper front part of the rectangularmain body 100, the mounting part 120 of the film retrieval cassette RCwhich is mounted on the lower front, the power supply means 130 betweenthe said mounting part 110 of the film feeding cassette and the saidmounting part 120 of the film retrieval cassette, the exposure means 140behind the power supply means 130 with the laser irradiation 141 headingtoward the back of the main body 100, the image processing control means150 which controls the image processing and operation of the equipmentat the front of the ceiling 100a, the pick-up mechanism 160 at theceiling in the position directly facing to the film outlet FCa of thefilm feeding cassette FC, the film conveyor means 170 at the back, andthe vibration isolating means 180 between the mounting part 120 of thefilm retrieval cassette and the bottom 100b of the main body 100.

For the mounting part 110 of the film feeding cassette, it is applicableto use the device which has, for instance, the opening 111 forthrusting/pulling out of the film feeding cassette FC on the main body100, and the supporters 112 which hold the film feeding cassette FC andenable it to slide in the direction to the back.

For the film feeding cassette FC, it is applicable to use the devicewhich is constructed to close the shutter and shut tightly the filmoutlet FCa when pulling out the film feeding cassette FC from themounting part 110, and to open the shutter and the film outlet FCa whenthrusting the film feeding cassette FC into the mounting part 110. Alsothe mounting part 110 of the film feeding cassette has the mechanism toclose/open the shutter in correspondence to the mounting motion of thefilm feeding cassette FC. For the film feeding cassette FC and themounting part 110 of the film feeding cassette with the construction,the device proposed in the Japanese Patent Application No. 306466/1992,for instance, is appropriate.

The film retrieval cassette RC and the mounting part 120 of the filmretrieval cassette should have the same construction as that of theabove mentioned film feeding cassette FC and the mounting part 110 ofthe film feeding cassette.

For the exposure means 140, it is applicable to use the scanning opticalsystem which is constructed to irradiate laser beams from thesemiconductor laser unit in response to the image signal sent from theimage processing control means 150, to reflect it with the polygonmirror, and to condense the reflected beams on the film surface with anfθ lens. For the exposure means 140 with the construction, the deviceproposed in the Japanese Patent Application No. 303104/1992, forinstance, is applicable, and for its exposure controller, the deviceproposed in the Japanese Patent Application No. 345507/1992, forinstance, is applicable.

The image processing control means 150 should be constructed to processgraphic data from an X-ray CT apparatus or an MRI, generate digitalgraphic data with variable density, generate enlarged or reduced graphicdata according to the graphic data, instruct to inscribe the image on adesignated location of the film F, and control the equipment. For theimage processing control means 150, it is applicable to use theapparatus with the controlling program for the other equipment, too.

For the pick-up mechanism 160, it is applicable to use a device whichhas a function to lift up/down and move a suction unit 161 by a liftingand moving device 162 as shown in FIGS. 18 and 19. To be more specific,it should be constructed as to hold the suction unit 161 on the arm 162which is crossed in a horizontal direction running near the ceiling 100aof the main body 100, and move the arm 162 tracing a designated locus bythe linking mechanism 163. The linking mechanism 163 should beconstructed, for example, as to rotate the Number 2 component 632centering around the fulcrum 632a by the Number 1 component 631, connectthe pin 634 and the pin 633 which is placed at the end of the arm 162 tothe long hole 632b formed at the end of the Number 2 component 632through the Number 3 component (not shown), lift up/down the pin 633along the guide groove 635, and simultaneously lift up/down the pin 634along with the guide groove 636.

The film conveyor means 170 comprises a film forwarding mechanism 171consisting of a pair of rollers, each positioned face to face, whichpicks the edge of the film F conveyed from the film feeding cassette FCby the above pick-up mechanism 160 and sends it out to the direction ofthe back of the main body 100, and which has a film collecting part 171apositioned facing the film F conveyed by the pick-up mechanism 160; anupper guide component 172 which changes the direction of the film Fconveyed to the back through the film collecting mechanism 171 to thedirection parallel with the back and has an inlet 172a and a guide face172b positioned facing the film discharging part 171b of the above filmforwarding mechanism 171; an upper forwarding mechanism 173 consistingof a pair of rollers, each positioned face to face, which has arecipient part 173a which sends the film F guided through the upperguide component 172 downward, parallel with the back, and faces theoutlet 172c of the above guide face 172b; a lower forwarding mechanism174 of the same construction positioned down from the upper forwardingmechanism 173 in a certain distance; the lower guide component 175comprising an inlet 175a which turns the film F discharged from thelower forwarding mechanism 174 to the film retrieval cassette RC and hasa guide face 175b facing the discharging part 174b of the aboveforwarding mechanism 174, the guide roller 175c positioned on the sideof the inlet 175a of the guide face 175b of the lower guide component175, a guide roller 175e positioned on the side of an outlet 175d; andthe film retrieval mechanism 176 comprising a pair of rollers, eachpositioned face to face, which sends out the film F guided from thelower guide component 175 to the film retrieval cassette RC and has therecipient part 176a facing the 175d of the above guide face 175.

It is adjusted so that the laser beams from the above exposure means 140irradiate between the upper forwarding mechanism 173 and the lowerforwarding mechanism 174 of the above conveyor means 170. While exposingthe film F with the exposure means 140, the front edge or the rear edgeof the film F sent out from the upper forwarding mechanism 173 curlsoutward, i.e. in the case of the drawing, in the direction of the backof the main body 100, with discharge of the bending stress generatedwhen the film F is bent by the guide surface 172b, resulting in unstableinscription on film. In this embodiment, therefore, a soft and pliablebelt 178, a little wider than the film F, is stretched between the rearone of the rollers 173c in the upper forwarding mechanism 173 and therear one of the rollers 174c in the lower forwarding mechanism 174, inorder to prevent the edge of the film F from curling. For material withpliability, it is applicable to use, for example, polyurethane, siliconrubber, neoprene rubber, or resin or fabric of these materials (forexample, woven fabric or nonwoven fabric of acetate, cotton, flax,nylon,or vinylon). It has a thickness of 0.2 to 0.5 mm and a width ofapprox. 400 mm. Its rubber hardness should show around 30 to 70 in scaledivision when measured with the spring-type hardness test machine(manufactured by Shimazu Corporation).

For the power supply means 130, a conventional device is used, and thedetailed explanation of its construction, therefore, is omitted here.

For the vibration isolating means 180, several vibration isolatingrubbers 181, for example, are placed at regular intervals.

As mentioned above, in this embodiment, the exposure means 140 ispositioned between the film cassette FC and RC so as to inscribe on thefilm F by irradiating laser beams toward the back of the main body 100where the film F is conveyed, and consequently it enables a minimizationof the height of the main body to about 400 mm and the weight to about60 kgs.

Following is a description of the procedure of exposure to the film F bythe variable density image photographic apparatus A with the abovementioned configuration:

Step 101: Pick up the edge of the film F from the film feeding cassetteFC through the pick-up mechanism 160, and convey it to the filmforwarding mechanism 171.

Step 102: The film forwarding mechanism 171 picks the edge of the film Fconveyed by the pick-up mechanism 160, and discharges it to the upperguide component 172.

Step 103: The upper guide component 172 changes the direction of thefilm F discharged through the film forwarding mechanism 171, and guidesit to the collecting part 173a of the upper forwarding mechanism 173.

Step 104: The upper forwarding mechanism 173 sends out the guided film Fdownward.

Step 105: After a certain portion of the film F is sent out through theupper forwarding mechanism 173, the exposure means 140 starts exposureby irradiating laser beams.

Step 106: The exposure means 140 starts scanning in the horizontaldirection at the same time when exposure starts. As the descending speedof the film F is very slow compared with the scanning speed in thehorizontal direction, it can be considered that the exposure means 140scans merely in the horizontal direction, thus bringing no practicalproblem in exposure.

Step 107: After completion of one scanning, the exposure means 140 stopsirradiation of laser beams, and puts the position to irradiate laserbeams back in its initial place.

Step 108: Step 106 and Step 107 are repeated in the fixed times, and theexposure to the film F, i.e. Inscription, is completed.

Step 109: The film F, after inscription, is collected into the filmretrieval cassette RC through the lower forwarding mechanism 174, thelower guide component 175, and the film retrieval mechanism 176.

As explained above, the variable density image (grey scale image)photographic apparatus in this embodiment enables exposure of the filmwhile it is being conveyed, and thus reduces inscription time of onecycle to about 15 seconds from 30 seconds that the conventionalapparatuses require. In short, it can cut the inscription time by half.

Industrial Applicability

As mentioned above, with the variable density image (grey scale image)processing method and the variable density image processing apparatus ofthis invention, it is possible to extract identifying data specific tothe film such as identification numbers, names of patients, or the imagecreation dates, from the images to be inscribed on film, enlarge thedata into a size readable by the unaided eye, and inscribe it at thebottom of film, for instance. Accordingly, it effectively works forquick processing of medical film.

Also, with the variable density image (grey scale image) photographicapparatus of this invention, size and weight of the apparatus can beeffectively reduced, thereby reducing space requirements. This secondaryeffect contributes to an efficient utilization of facilities.Furthermore, with a smaller and more light weight body, costs involvedin manufacture and shipping of apparatuses are remarkably reduced. Also,in the preferable aspect of the variable density image (grey scaleimage) photographic apparatus in this invention, exposure to film duringfilm conveyance is achieved and the time required for inscription iseffectively reduced by half.

We claim:
 1. A variable density image (grey scale image) photographicapparatus for forming a variable density image on a film supplied from afilm feeding cassette by exposing a laser beam thereto, and retrievingthe film into a film retrieving cassette under the film feedingcassette, said apparatus comprising:an exposure means for projecting alaser beam to the film, said exposure means including a laser beamscanning system, and being located between the film feeding cassette andfilm retrieving cassette; a film conveyor means for conveying the filmfrom the film feeding cassette to the film retrieving cassette through alaser beam projecting area; and a control means for controlling theexposure means and film conveyor means, said control means being locatedabove the film feeding cassette.
 2. The variable density image (greyscale image) photographic apparatus of claim 1, wherein the film isexposed by said exposure means while being conveyed by said filmconveyor means.
 3. The variable density image (grey scale image)photographic apparatus of claim 1, wherein the film conveyor meansinclude at least one pair of rollers stretched over a soft and pliablebelt, somewhat wider than the film conveyed, on a curling side of thefilm.
 4. The variable density image (grey scale image) photographicapparatus of claim 2, wherein the film conveyor means include at leastone pair of rollers stretched over a soft and pliable belt, somewhatwider than the film conveyed, on a curling side of the film.
 5. Thevariable density image (grey scale image) photographic apparatus ofclaim 3, wherein said belt passes through the laser beam projectingarea.
 6. The variable density image (grey scale image) photographicapparatus of claim 4, wherein said belt passes through the laser beamprojecting area.